/* ************************************************************************
 * Copyright (c) 2018 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * ************************************************************************ */

#include "../../utils/def.hpp"
#include "preconditioner_multielimination.hpp"
#include "preconditioner.hpp"
#include "../solver.hpp"

#include "../../base/local_matrix.hpp"

#include "../../base/local_vector.hpp"

#include "../../utils/log.hpp"
#include "../../utils/math_functions.hpp"

#include <complex>

namespace rocalution {

template <class OperatorType, class VectorType, typename ValueType>
MultiElimination<OperatorType, VectorType, ValueType>::MultiElimination()
{
    log_debug(this, "MultiElimination::MultiElimination()", "default constructor");

    this->diag_solver_init_ = false;
    this->level_            = -1;
    this->drop_off_         = 0.0;
    this->size_             = 0;

    this->AA_me_     = NULL;
    this->AA_solver_ = NULL;

    this->AA_nrow_ = 0;
    this->AA_nnz_  = 0;

    this->op_mat_format_      = false;
    this->precond_mat_format_ = CSR;
}

template <class OperatorType, class VectorType, typename ValueType>
MultiElimination<OperatorType, VectorType, ValueType>::~MultiElimination()
{
    log_debug(this, "MultiElimination::~MultiElimination()", "destructor");

    this->Clear();
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::Clear(void)
{
    log_debug(this, "MultiElimination::Clear()", this->build_);

    if(this->build_ == true)
    {
        this->A_.Clear();
        this->D_.Clear();
        this->C_.Clear();
        this->E_.Clear();
        this->F_.Clear();
        this->AA_.Clear();

        this->A_.ConvertToCSR();
        this->D_.ConvertToCSR();
        this->C_.ConvertToCSR();
        this->E_.ConvertToCSR();
        this->F_.ConvertToCSR();
        this->AA_.ConvertToCSR();

        this->AA_nrow_ = 0;
        this->AA_nnz_  = 0;

        this->x_.Clear();
        this->x_1_.Clear();
        this->x_2_.Clear();

        this->rhs_.Clear();
        this->rhs_1_.Clear();
        this->rhs_1_.Clear();

        this->permutation_.Clear();

        if(this->AA_solver_ != NULL)
        {
            this->AA_solver_->Clear();
        }

        if(this->AA_me_ != NULL)
        {
            delete this->AA_me_;
        }

        this->diag_solver_init_ = false;
        this->level_            = -1;
        this->drop_off_         = 0.0;
        this->size_             = 0;

        this->AA_me_     = NULL;
        this->AA_solver_ = NULL;

        this->op_mat_format_      = false;
        this->precond_mat_format_ = CSR;

        this->build_ = false;
    }
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::Print(void) const
{
    if(this->build_ == true)
    {
        LOG_INFO("MultiElimination (I)LU preconditioner with " << this->GetLevel()
                                                               << " levels; diagonal size = "
                                                               << this->GetSizeDiagBlock()
                                                               << " ; drop tol  = "
                                                               << this->drop_off_
                                                               << " ; last-block size = "
                                                               << this->AA_nrow_
                                                               << " ; last-block nnz = "
                                                               << this->AA_nnz_
                                                               << " ; last-block solver:");

        this->AA_solver_->Print();
    }
    else
    {
        LOG_INFO("MultiElimination (I)LU preconditioner");
    }
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::Set(
    Solver<OperatorType, VectorType, ValueType>& AA_Solver, int level, double drop_off)
{
    log_debug(this, "MultiElimination::Set()", (const void*&)AA_Solver, level, drop_off);

    assert(level >= 0);

    this->level_     = level;
    this->AA_solver_ = &AA_Solver;
    this->drop_off_  = drop_off;
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::SetPrecondMatrixFormat(
    unsigned int mat_format)
{
    log_debug(this, "MultiElimination::SetPrecondMatrixFormat()", mat_format);

    this->op_mat_format_      = true;
    this->precond_mat_format_ = mat_format;
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::Build(void)
{
    log_debug(this, "MultiElimination::Build()", this->build_, " #*# begin");

    assert(this->build_ == false);
    this->build_ = true;

    assert(this->op_ != NULL);
    assert(this->AA_solver_ != NULL);

    this->A_.CloneBackend(*this->op_);
    this->D_.CloneBackend(*this->op_);
    this->C_.CloneBackend(*this->op_);
    this->E_.CloneBackend(*this->op_);
    this->F_.CloneBackend(*this->op_);
    this->AA_.CloneBackend(*this->op_);

    this->inv_vec_D_.CloneBackend(*this->op_);
    this->vec_D_.CloneBackend(*this->op_);

    this->x_.CloneBackend(*this->op_);
    this->x_1_.CloneBackend(*this->op_);
    this->x_2_.CloneBackend(*this->op_);

    this->rhs_.CloneBackend(*this->op_);
    this->rhs_1_.CloneBackend(*this->op_);
    this->rhs_1_.CloneBackend(*this->op_);

    this->permutation_.CloneBackend(this->x_);

    this->A_.CloneFrom(*this->op_);

    //  this->A_.ConvertToCSR();

    this->A_.MaximalIndependentSet(this->size_, &this->permutation_);

    this->A_.Permute(this->permutation_);

    this->A_.ExtractSubMatrix(0, 0, this->size_, this->size_, &this->D_);

    this->A_.ExtractSubMatrix(
        0, this->size_, this->size_, this->A_.GetLocalN() - this->size_, &this->F_);

    this->A_.ExtractSubMatrix(
        this->size_, 0, this->A_.GetLocalM() - this->size_, this->size_, &this->E_);

    this->A_.ExtractSubMatrix(this->size_,
                              this->size_,
                              this->A_.GetLocalM() - this->size_,
                              this->A_.GetLocalN() - this->size_,
                              &this->C_);

    this->A_.Clear();

    this->D_.ExtractInverseDiagonal(&this->inv_vec_D_);
    this->D_.ExtractDiagonal(&this->vec_D_);

    this->E_.DiagonalMatrixMult(this->inv_vec_D_); // E =  E * D^-1

    this->AA_.MatrixMult(this->E_, this->F_); // AA = E * D^-1 * F

    //  this->AA_.ScaleDiagonal(-1.0);
    //  this->AA_.ScaleOffDiagonal(-1.0);
    //  this->AA_.MatrixAdd(this->C_);

    // AA = C - E D^-1 F
    this->AA_.MatrixAdd(this->C_, static_cast<ValueType>(-1), static_cast<ValueType>(1), true);

    this->C_.Clear();

    if(this->drop_off_ > 0.0)
    {
        this->AA_.Compress(this->drop_off_);
    }

    this->AA_nrow_ = this->AA_.GetLocalM();
    this->AA_nnz_  = this->AA_.GetLocalNnz();

    if(this->level_ > 1)
    {
        // Go one level lower

        this->AA_me_ = new MultiElimination<OperatorType, VectorType, ValueType>;
        this->AA_me_->SetOperator(this->AA_);
        this->AA_me_->Set(*this->AA_solver_, this->level_ - 1, this->drop_off_);

        this->AA_me_->Build();

        this->AA_solver_ = this->AA_me_;
    }
    else
    {
        // level == 0
        // set solver

        this->AA_solver_->SetOperator(this->AA_);
        this->AA_solver_->Build();
    }

    this->x_.CloneBackend(*this->op_);
    this->x_.Allocate("Permuted solution vector", this->op_->GetM());

    this->rhs_.CloneBackend(*this->op_);
    this->rhs_.Allocate("Permuted RHS vector", this->op_->GetM());

    this->x_1_.CloneBackend(*this->op_);
    this->x_1_.Allocate("Permuted solution vector", this->size_);

    this->x_2_.CloneBackend(*this->op_);
    this->x_2_.Allocate("Permuted solution vector", this->op_->GetM() - this->size_);

    this->rhs_1_.CloneBackend(*this->op_);
    this->rhs_1_.Allocate("Permuted solution vector", this->size_);

    this->rhs_2_.CloneBackend(*this->op_);
    this->rhs_2_.Allocate("Permuted solution vector", this->op_->GetM() - this->size_);

    if(this->level_ > 1)
    {
        this->AA_.Clear();
    }

    // Clone the format
    // e.g. the block matrices will have the same format as this->op_
    if(this->op_mat_format_ == true)
    {
        A_.ConvertTo(this->precond_mat_format_);
        D_.ConvertTo(this->precond_mat_format_);
        E_.ConvertTo(this->precond_mat_format_);
        F_.ConvertTo(this->precond_mat_format_);
        //    C_.ConvertTo(this->precond_mat_format_);
        //    AA_.ConvertTo(this->precond_mat_format_);
    }

    log_debug(this, "MultiElimination::Build()", this->build_, " #*# end");
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::Solve(const VectorType& rhs,
                                                                  VectorType* x)
{
    log_debug(this, "MultiElimination::Solve()", " #*# begin", (const void*&)rhs, x);

    assert(this->build_ == true);

    this->rhs_.CopyFromPermute(rhs, this->permutation_);

    this->x_1_.CopyFrom(this->rhs_, 0, 0, this->size_);

    this->rhs_2_.CopyFrom(this->rhs_, this->size_, 0, this->rhs_.GetLocalSize() - this->size_);

    // Solve L
    this->E_.ApplyAdd(this->x_1_, static_cast<ValueType>(-1), &this->rhs_2_);

    // Solve R
    this->AA_solver_->SolveZeroSol(this->rhs_2_, &this->x_2_);

    this->F_.ApplyAdd(this->x_2_, static_cast<ValueType>(-1), &this->x_1_);

    this->x_1_.PointWiseMult(this->inv_vec_D_);

    this->x_.CopyFrom(this->x_1_, 0, 0, this->size_);

    this->x_.CopyFrom(this->x_2_, 0, this->size_, this->rhs_.GetLocalSize() - this->size_);

    x->CopyFromPermuteBackward(this->x_, this->permutation_);

    log_debug(this, "MultiElimination::Solve()", " #*# end");
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::MoveToHostLocalData_(void)
{
    log_debug(this, "MultiElimination::MoveToHostLocalData_()", this->build_);

    this->A_.MoveToHost();
    this->D_.MoveToHost();
    this->C_.MoveToHost();
    this->E_.MoveToHost();
    this->F_.MoveToHost();
    this->AA_.MoveToHost();

    this->x_.MoveToHost();
    this->x_1_.MoveToHost();
    this->x_2_.MoveToHost();

    this->rhs_.MoveToHost();
    this->rhs_1_.MoveToHost();
    this->rhs_2_.MoveToHost();

    this->inv_vec_D_.MoveToHost();

    this->permutation_.MoveToHost();

    if(this->AA_me_ != NULL)
    {
        this->AA_me_->MoveToHost();
    }

    if(this->AA_solver_ != NULL)
    {
        this->AA_solver_->MoveToHost();
    }
}

template <class OperatorType, class VectorType, typename ValueType>
void MultiElimination<OperatorType, VectorType, ValueType>::MoveToAcceleratorLocalData_(void)
{
    log_debug(this, "MultiElimination::MoveToAcceleratorLocalData_()", this->build_);

    this->A_.MoveToAccelerator();
    this->D_.MoveToAccelerator();
    this->C_.MoveToAccelerator();
    this->E_.MoveToAccelerator();
    this->F_.MoveToAccelerator();
    this->AA_.MoveToAccelerator();

    this->x_.MoveToAccelerator();
    this->x_1_.MoveToAccelerator();
    this->x_2_.MoveToAccelerator();

    this->rhs_.MoveToAccelerator();
    this->rhs_1_.MoveToAccelerator();
    this->rhs_2_.MoveToAccelerator();

    this->inv_vec_D_.MoveToAccelerator();

    this->permutation_.MoveToAccelerator();

    if(this->AA_me_ != NULL)
    {
        this->AA_me_->MoveToAccelerator();
    }

    if(this->AA_solver_ != NULL)
    {
        this->AA_solver_->MoveToAccelerator();
    }
}

template class MultiElimination<LocalMatrix<double>, LocalVector<double>, double>;
template class MultiElimination<LocalMatrix<float>, LocalVector<float>, float>;
#ifdef SUPPORT_COMPLEX
template class MultiElimination<LocalMatrix<std::complex<double>>,
                                LocalVector<std::complex<double>>,
                                std::complex<double>>;
template class MultiElimination<LocalMatrix<std::complex<float>>,
                                LocalVector<std::complex<float>>,
                                std::complex<float>>;
#endif

} // namespace rocalution
